Filter clogging indicator



May 22, 1956 R. H. AUFDERHEIDE FILTER CLOGGING INDICATOR Filed June 23, 1954 u Fh s l QM, l TTORNEV L 7 w/ M K, H2M n.. f

llnvz-:Nron IPICHARD H .AUFDERHEIDE 2,746,416 i Patented 22,1956

United States Paten-t "()ffice 2,746,416 n FILTER ,croGGrNG INDICATOR Richard H. Aufderheide, `Indianapolis, 1nd., assigner to Rfer Metal-Craft,'Inc., Indianap.olis, Ind., a corporation o ndiana n i Application. .June 2.3, 1.95.4, Serial No. 438,818.

charges air into a plenum chamber for distribution into the warm air ducts, the filter being at the cold air intake `from the various spaces being heated. Filters located in such places are subject to being clogged by lint and dirt being taken from the spaces, and when the filter becomes too seriously clogged, then the fan or blower is unable to deliver the proper pressure in the pleunm chamber to effect the carrying of the warm air into the spaces for heating. The circulation of the air from the cold air ducts over the heating areas in the furnace and back into the spaces to be heated is seriously impaired by a dirty filter.

By use of my device, the condition of the filter is readily determined simply by a glance at the indicating part of the device so thatthe filter itself does not have to be pulled out and inspected to determine its actual condition Vof dirt coverage or penetration.

My device also lends itself to easy installationon the furnace and may be produced at a relatively low cost. The use of the device embodying the invention generally means the difference betweena very ineffective and a most efficient heating system because the condition of the filter is made apparent at a glance whereas a dirty filter is generally allowed to remain in that condition over too long a period of time.

These and many other objects and advantages of the invention will become apparent to those versed in the art in the following description of one particular form of the invention, as illustrated in the accompanying drawins, in which,

Fig. 1 is a4 View in front elevation and partial section of a structure embodying the invention;`

Fig. 2 is a vertical section on the line 2-2 in Fig. 1;

Fig. 3 is a view in detail in top plan and transverse section of the mounting of the shiftable vane;

Fig. 4 is a detail in vertical section on the line 4 4 in Fig. l;

Fig. 5 is a view in bottom plan of the device in partial section; and

Fig. 6 is a view in side elevation and partial section on a reduced scale of the device as mounted on a plenum chamber.

A housing generally indicated by the numeral 10 is formed to have a horizontally disposed transverse partition 11 spaced above the oor 12. An opening 13 is provided through the partition 11, and a shaft 14 is rockably mounted substantially centrally across this opening by having its end portions carried in bearing beads 15 and 16. These beads 15 and 16 are of a diameter somewhat larger than the width of the opening 14 so that by a limited circumferential portion thereof in each instance, these beads 15 and 16 are held against rolling out of the opening, and this positioning is maintained ceives the discharge of the blower of the furnace. The

by means of hold. down clip wires 17 and 18, Fig. vEl, which have end portions rockably carried under rivet heads 19 and 20. The other end portions of these wire clips 17 and 18 are curved as at 21,' Fig. 1, to rest over the top sides of the `beads 15 and 16 so as t0 retain them in position.

A vane 22 is secured by an upper end to the shaft 14 and this vane 22 is thus free to rock with the shaft 14 supported through the beads 15 and 16. The lower end portion of the vane.22, Fig. 1, is preferably carried to within close proximity with the iioor 12, and has a lower rounded lip 23 extending from the lower end portion in an arcuate manner. The lip 23 is turned generally around and slightly upwardly.

The upper portion of the vane 22 terminates in a generally rectangular plate 24, Fig. 2, from which extends a needle or finger 25 to the uppermost portion of the housing 10, so that the pointer 25 is free to rock as the vane 22 may be rocked under the partition 11. The pointer 25 as described extends above the partition 11, and sweeps with a clearance over the dial 26 which is mounted on the back wall 27 of the housing 10, to extend upwardly and outwardly therefrom in a substantially Vertical plane.

The upper portion of the dial 26 carries certain indicia thereon as illustrated in Fig. l, such that when the vane 22 and the pointer 25 are in their normal positions of rest which positions are as those indicated in Fig. l when the furnace blower is not in operation. In these positions, the pointer 25 will be over the indicia indicating that the blower is off. Then there is a circumferential area 28 carrying the wording in the present instance of Stopped Up and` Replace When the pointer 25 is over that area 28, the indication is when the furnaceis running that the filter is in that state of clogging with dust wherein it should be replaced. Then next adjoining the area 28 is a third area 29 c yying the wording Dirty Dusty and Time to Clean. In other words, when the pointer 25 is over the area 29, the indication thereby given is that the filter should be cleaned so that it can be continued in use. Then the last area 30 to the right of the area 29 is that area over which theV pointer 25 will go when the filter is new and is clean so that the minimum and normal resistance to air is had in owing therethrough. I l

Since the partition 1 1 extends entirely horizontally across the housing 10 there is the lower compartment 31 defined between that partition, the baclr-wall-27, the oor 12, and a front wall 33 turning downwardly from the partition 11 into Contact with4 the' floor- 12. The vane 22 may rock that' compartment 31. At one end of the compartment" 31, there. is a tube 34 carried across the compartment to have an inner closed end 35 and an distance and is preferably terminated in a diagonal plane.

This tube 34 is located out of the permissible travel of the vane 22.

On the other side of the vane 22, the compartment 31 continues with the same cross-sectional area to the op, posite side of the housing 10. In that portion of the compartment 31, there is provided a window 38 through the door 12. A front cover 40 with sides 41 and 42 is attached to the housing 10 to complete the structure.

The structure above described is mounted on the furnace in any suitable position Where it is subjected to the discharge side of the blower. Normally this would be the plenum chamber, as illustrated in Fig. 6, which rehousing 10 is mounted against the outside wall 43 of the plenum chamber to have the tube 34 extending inwardly thereof so as to place the compartment 31 into com.,

mittedtozthe compartment 31, so thatthe vane 2.2"is

tendedtozbe;rockedbyitslower end toward the window 38. The air tends to discharge through the tube 34, `the-window 36,andaround the vane 22 which is somejwhat looselyicarriedriwithin "the compartment 31, and

then out the window 38 into. the atmosphere. The rate V f1iiowpf vthe air from the plenumchamber through the compartment" 31 in the manner `just described will' determine the'degreegof'rocking ofthe vane'22, andcorrespondingly;thedegreezof rockingV of the pointer 25.

When air is restritedfinf'ow'through the lter, the blewercannotv exertgasxmuch"pressure in the plenum Vchamberas"itfwould.when. the filter is clean, and consequently;the-'pressure'inl theplenum chamber will vary in accordance with-V thedegree` of clogging of the filter. In this manner, lthe positioning of the pointer 25 will be intiuenced by the pressure in the plenum chamber.

Each furnacev system will vary in respect to the air .pressures thereinV independently of the filter restriction Adepending upon several factors, including among others, the length of the air ducts, the cross-sectional area of the ducts, and lter construction: Also there will of necessity-be diierent locations at which my indicator may be applied, the location not always being at the plenum chamber.V f 3v To correlate theindicator with the individual furnace system, I provide means fforvarying the effective size of the opening 36 out of the tube34 to control the travel lof the needle 25.'v One` particular form of such means consistsuof a tubular sleeve 45 which surrounds and frictionally engages that portion of the tube 34 which will extend across the compartment or tunnel 31. This sleeve 45 is lclosed at its front YendY by the closure head 46 which 4carries a slot 47;,thereacross as a means by use of a tool such as a screw driver to revolve the sleeve 45 circumferentially around the tube 34. The sleeve 45 has an opening 48 along one side with a surrounding margin conforming in shape and extent to coincide with the margin of the tube opening 36 when the sleeve A451is so turned. This giveswmaximum air ilow from the'tube 34 y through the compartment 31.

By revolving the sleeve 45, the effective area of the opening 36 maybe varied from that full size to a reduced or fractional size,` whereby the` indicator may be calibrated from its front side after installation to give a needle travel in accordance iwith the actual furnace ilter condition, so that thev sweep of the finger will remain within theconiines of theV dial, and also whereby but one indicator dial or card 2 6 is required for all installations.

While I havehereinshown and described my invention in the one particular form, it is obvious that structural changes may be employed without departing from the spirit of the invention, and I therefore do not desire to be limited to that precise form beyond the limitations which may be imposed -by the following claims.

I claim: v

1. An indicatorv for indicating degree of air ow through a filter in the air intake conduit of a blower in a forced air ow type. heating'furnace, indicating only during operation of the blower,'comprising a housing; a vane rockably supported on an axis transversely extending across the upper sidey of the housingV to have the vane hang downwardly andy swing freely therein; a needle extending generally upwardly from and fixed in relation to said vane to swing therewith; an indicia card traversed by said needle within the limits of swinging of s aid vane;

`a tube entering said' housing to one'side ofv said vane and open from its outer end,y and further having an opening within the housing; means adjustably varying the area of said opening within Ithe housing for individual furnace conditions; said tube by its outer end connecting to said furnace on the discharge sideof said blower; said housing having an opening on the other side of said vane removed from said tube and'discharging into the atrnosphere; said vane and 'needle being in effect an integral unit and of distributedweight from said axis to induce by gravity a return of the needle always to an end position on said card when said blower isinoperative.

2. The structure of claim-1 in which said vane by its lower endapproaches closely tothe floor of said housing andY turnsup therefrom by an'arcuate portion on the vane side toward said tube.

3. The structure of claim 1 in which said housing is rectangular and has a'ftransverse slot across its upper side; a pair of spaced apart beads resting above and across the.y margins yof said s1ot;a shaft rotatably carried by ends inserted in .said beads; means maintaining said beads in position over the slot; said axis coinciding with the axis of s'aid shaft,'.and said vane being fixed to said shaft;

4. The structure of. claim 1 in which said tube opening is through its circumferential side and said adjustable means comprisesv a. closed end. sleeve having a side opening and telescoping revolubly with said tube within said housing to have said tube and sleeve opening selectively register circumferentially upon revolving the sleeve in respect to the tube.`

References fCited in'thele of this patent UNTTED STATES PATENTS l 

